A transformer has become an essential electronic component for regulating an input voltage into voltages required for various kinds of electric appliances.
FIG. 1A is a schematic exploded view illustrating a conventional transformer. As shown in FIG. 1A, the transformer 1 comprises a bobbin 11, a covering member 12, and a magnetic core assembly 13. A primary winding coil 111 and a secondary winding coil 112 are wound on the bobbin 11. The outlet terminals 113, 114 of the primary and the secondary winding coils 111, 112 are directly wound and soldered on the connecting parts 117 of the pins 118. The insertion parts 115 of the pins 118 are inserted into conductive holes of a system circuit board (not shown). The covering member 12 is used for partially sheltering the upper portion of the bobbin 11 in order to increase the creepage distances between the primary winding coil 111, the secondary winding coil 112 and the magnetic core assembly 13. The magnetic core assembly 13 includes middle portions 131 and leg portions 132. The middle portions 131 are accommodated within a channel 116 of the bobbin 11. The bobbin 11 is partially enclosed by the leg portions 132. Meanwhile, the transformer 1 is assembled.
Please refer to FIG. 1A again. The transformer 1 is electrically connected with the system circuit board through the connecting parts 117 and the insertion parts 115 of the pins 118. Since each pin 118 includes a connecting part 117 and an insertion part 115, the pin 118 is L-shaped. The outlet terminals 113 and 114 are wound and soldered on the connecting parts 117. Via the connecting parts 117 and the insertion parts 115, the outlet terminals 113 and 114 are electrically connected with the system circuit board. Although the L-shaped pins 118 are effective for electrically connecting the outlet terminals 113 and 114 with the system circuit board, there are still some drawbacks. For example, during the transformer 1 is mounted on the system circuit board, the L-shaped pins 118 are readily shifted. In this situation, the outlet terminals 113 and 114 are possibly broken and detached from the connecting parts 117. As known, the increase of wire diameter of the primary winding coil 111 and the secondary winding coil 112 may reduce the possibility of breaking the outlet terminals 113 and 114. However, since the wire diameter is increased, the turn numbers of the primary winding coil 111 and the secondary winding coil 112 may be insufficient to achieve the required inductance. For complying with the increased wire diameter, the bobbin 11 needs to be re-designed and re-produced. The process of re-designing and re-producing the new bobbin is time-consuming and costly.
Moreover, since the connecting parts 117 of the L-shaped pins 118 are arranged at the same level and adjacent to each other, the outlet terminals 113 and 114 soldered on the connecting parts 117 are readily contacted with each other. In this situation, a short-circuited problem occurs.
FIG. 1B is a schematic assembled and rear view illustrating the transformer of FIG. 1A. For winding the primary winding coil 111 on the bobbin 11, an outlet terminal of the primary winding coil 111 is firstly soldered on a connecting part 117 of a pin 118. Then, the primary winding coil 111 is partially accommodated within the wire-arranging groove 119. Then, the primary winding coil 111 is wound around the winding section of the bobbin 11. The process of winding the secondary winding coil 112 on the bobbin 11 is similar to the process of winding the primary winding coil 111 on the bobbin 11, and is not redundantly described herein.
Please refer to FIG. 1B again. Since the remaindering winding coil may frequently rub against an initial winding segment 1111 of the primary winding coil 111 during the winding coil is wound on the first winding section, the insulated varnish (not shown) coated on the initial winding segment 1111 of the primary winding coil 111 is possibly abraded off. In this situation, the insulating efficacy of the primary winding coil 111 is insufficient, and thus an instantaneous spike problem occurs.
Therefore, there is a need of providing an improved bobbin of a transformer so as to obviate the drawbacks encountered from the prior art.